This invention relates to a four-cycle watercraft engine and more particularly to an improved induction system for such engines.
There is a very popular type of small watercraft that is designated as a "personal" watercraft. This type of watercraft is quite compact in nature and frequently accommodates the operator and/or passengers seated in a straddle fashion. Where more than one occupant is present, the occupants frequently ride in a tandem fashion.
It has been generally the practice to employ as prime movers for such watercraft two-cycle engines. Two-cycle engines have a number of advantages, the prime of which is the relatively compact construction of such engines. In addition, with crankcase compression two-cycle engines, the induction and exhaust systems can be positioned relatively low on the engine and thus the engine can be quite compact in configuration.
This compact configuration is particularly important when the engine is disposed so that it is positioned beneath the seat of the watercraft. Using the tandem straddle-type seat arrangement, the seat is relatively narrow and tapers outwardly in a downward direction. Hence, two-cycle engines are particularly adapted for positioning beneath such seats.
There are, however, certain reasons why four-cycle engines may be more advantageous for use in such watercraft. Four-cycle engines may, in some instances, be more environmentally friendly and thus they are being considered for this type of application.
However, a four-cycle engine, particularly a high output engine, has the induction and exhaust system normally positioned at the upper end of the engine and generally mounted directly to the cylinder head. Thus, unlike a two-cycle engine where the induction and exhaust systems are difficulties in positioned low and adjacent the crankshaft, four-cycle engines place these components higher in the cylinder block or directly on the cylinder head. This gives rise to positioning the engine under a seat of the aforenoted type.
It is, therefore, a principal object of this invention is to provide an improved four-cycle engine configuration that lends itself for use in personal type watercraft.
It is a further object of this invention to provide an improved, compact induction system and layout for a four-cycle engine.
It is a further object of this invention to provide an improved, compact induction system for a four-cycle internal combustion engine so as to adapt it for watercraft usage.